The present invention relates to an insulating construction form for the building of structural walls. Construction forms are employed to act as a mold for a poured concrete charge in making walls of the like. Typically, the forms comprise a pair of spaced panels that define an outer surface of the walls and the forms are intended to be removed once the concrete is set. More recently, consideration has been given to thermal properties of the walls and the need to incorporate thermal insulation in the walls.
Many variations on the design of a construction form for insulated walls have been disclosed in the art. Prior art design of construction forms is exemplified by U.S. Pat. Nos. 4,706,429, 5,598,675, and 5,390,459, all of which include a pair of high density foam panels spaced apart by a series of bridging ties. A reinforcing bar, or rebar, is positioned between the panels and is supported by the ties. The ties comprise a pair of endplates connected by a web, and are typically made of an insulating material such as plastic in order to inhibit thermal bridging between the panels.
Young, in U.S. Pat. No. 4,706,429, teaches the employment of an interconnecting mechanism consisting of a series of projections and corresponding recesses on a top and a bottom surface of the panels. When the construction forms are stacked in vertical layers, the interlocking projections and corresponding recesses provide a concrete impervious seam during charging. One inadequacy of the current interconnect design is that the stacked layers can separate during charging due to hydrodynamic forces of the concrete, and also during stacking of the constructions forms in windy conditions.
Mensen, in U.S. Pat. No. 5,390,459, and Pruss, in U.S. Pat. No. 5,598,675, both teach the deployment of adjacent receptacles at the top of the tie, defined by a series of arms, for the positioning of the rebar. Multiple receptacles are required for rebar positioning, since rebar is frequently curved along its length due to handling. The rebar may therefore be misaligned with an inline series of receptacles, positioned longitudinally along the construction form. In certain instances, a number of arms must be removed to accommodate for misalignment of the rebar. Pruss teaches detachable arms but their removal may tear the web, which can result in cracking of the web during charging. Mensen""s arms cannot be removed as they are integral with the web.
Both Mensen and Pruss disclose arms with hooks framing the receptacle on either side, to help retain the rebar in position during charging. The inclusion of this retention feature permits a limited number of rebar sizes to be used with any one size of receptacle, due to the rigidity of the arms. Removal of any of Pruss"" retaining arms between the receptacles, results in an oversized receptacle which is detrimental to the retaining feature and may result in the loss thereof. When the retaining feature of the arms is absent, the rebar is not held as securely and therefore may shift during charging.
There are many designs in the prior art, where the insulating construction form serves for a formation of a corner, typically 90xc2x0. Typically the endplates of the ties provide the retention for fasteners, but traditional placement of the ties in the prior art results in the corner region of a construction form being devoid of any internal supports, to which a cladding such as drywall and exterior siding can be secured.
It is therefore an objective of the present invention to provide an insulating construction form that will obviate or mitigate the above disadvantages.
In one aspect of the invention, there is provided an insulating construction form comprising a pair of panels made of an insulating material arranged in a spaced parallel relationship with their inner surfaces facing each other, and a number of bridging ties extending between and embedded in the panels. Each of the panels include an inside surface and an outside surface, a top surface and a bottom surface. Each of the ties comprises a pair of elongated end plates that are integral with at least one web, which extends between and is connected to the end plates. Each of the end plates may be embedded between the inside and outside surfaces of each of the panels. The webs include at least one retainer arm located along the web. Each of the receptacles include a pair of retainer arms for locating and retaining a reinforcing bar between the arms.
Located at the top of each arm is a hooked barb which is angled, in a downward and inward orientation towards the interior of the corresponding receptacle. A spine may be attached to the back of the arm, disposed perpendicular therefrom. The barbs, along with the resilient nature of the arms, help to provide a snap fit for the reinforcing bar when positioned in the receptacle. This snap fit inhibits movement of the reinforcing bar out of the receptacle during installation and subsequent pouring of the charge. Attached to the side of the web may be a series of guides, which can assist in positioning of the ties in a mold during formation of the panels. A plurality of ridges may also be located on the side of the web to stiffen the web.
In a further aspect, the retaining function of the barbs is accomplished by abutment surfaces, preferably located at the end of the retaining arms and arcuate shaped.
In employment of the construction form, a plurality of forms are stacked in layers in an overlapping manner to form a wall. In another aspect of the invention the top surface and the bottom surface of the panels include an interconnecting mechanism comprising a plurality of projections and a plurality of corresponding recesses. The insertion of the projections into the corresponding recesses provides an interference fit between adjacent forms stacked in a vertical manner, in order to inhibit separation of the forms during installation such as in windy conditions or during charging.
A further aspect of the retainer arms is the inclusion of a weakening notch, in the preferred embodiment, which allows arms to be easily removed from the web in order to accommodate an irregularly shaped reinforcing bar, without excessive damage to the body of the web.
Once construction of the wall is completed the charge, typically concrete or other suitable building materials may be poured into the interior and allowed to set, thereby producing an insulated structural wall. A plurality of markings on the exterior surface of the construction form may be used to guide the location of fasteners, such as screws or nails. The fasteners are used to attach a cladding such as drywall or metal siding, to the end plates preferably embedded in the panels.
In a further aspect of the invention, at least one of the panels is divided into a first portion and a second portion disposed at angle to define a corner. The corner has a substantially vertical duct extended between the top and the bottom surfaces of the panel located preferably adjacent to the apex of the corner. A solid or hollow rod may be inserted into the duct. The rod provides an anchor in the interior of the panel for the attachment of the exterior cladding in the corner region.
Frictional grip between the side walls of the duct and the rod also helps to create an integral vertical formation during installation of the layered construction forms and subsequent charging. The rod can be made of any suitable material, such as wood, metal or plastic.
In another aspect of the invention, a method of molding an insulating form comprising the steps of formation of a pair of panels made of an insulating material and having an inside surface and an outside surface, a top surface and a bottom surface. The panels are arranged in a spaced parallel relationship with their inner surfaces facing each other. Provided in at least one of the panels is a plurality of apertures, each of which extends between the inside and outside surfaces of the panel. The panels are connected by at least two bridging ties extending between the panels. The connection includes embedding a pair of end plates integrally formed with at least one web in the panels, wherein each of the end plates is located between the inside and the outside surfaces of each of the panels. The method of molding the panels includes the step of forming the apertures at the time molding the panels and an interior surface of the apertures may be lined with a liner, made of a suitably rigid material, such as plastic or metal.